change API contract: disallow zero-sized images or surfaces

BUG=skia:

Review URL: https://codereview.chromium.org/830033003

4 files changed, 12 insertions, 33 deletions

diff --git a/src/image/SkImage_Raster.cpp b/src/image/SkImage_Raster.cpp
index a06cca6e9b..0ee391464f 100644
--- a/src/image/SkImage_Raster.cpp
+++ b/src/image/SkImage_Raster.cpp
@@ -19,7 +19,7 @@ public:
         const int maxDimension = SK_MaxS32 >> 2;
         const size_t kMaxPixelByteSize = SK_MaxS32;
 
-        if (info.width() < 0 || info.height() < 0) {
+        if (info.width() <= 0 || info.height() <= 0) {
             return false;
         }
         if (info.width() > maxDimension || info.height() > maxDimension) {
@@ -49,8 +49,6 @@ public:
         return true;
     }
 
-    static SkImage* NewEmpty();
-
     SkImage_Raster(const SkImageInfo&, SkData*, size_t rb, const SkSurfaceProps*);
     virtual ~SkImage_Raster();
 
@@ -86,16 +84,6 @@ private:
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkImage* SkImage_Raster::NewEmpty() {
-    // Returns lazily created singleton
-    static SkImage* gEmpty;
-    if (NULL == gEmpty) {
-        gEmpty = SkNEW(SkImage_Raster);
-    }
-    gEmpty->ref();
-    return gEmpty;
-}
-
 static void release_data(void* addr, void* context) {
     SkData* data = static_cast<SkData*>(context);
     data->unref();
@@ -169,14 +157,7 @@ bool SkImage_Raster::getROPixels(SkBitmap* dst) const {
 ///////////////////////////////////////////////////////////////////////////////
 
 SkImage* SkImage::NewRasterCopy(const SkImageInfo& info, const void* pixels, size_t rowBytes) {
-    if (!SkImage_Raster::ValidArgs(info, rowBytes)) {
-        return NULL;
-    }
-    if (0 == info.width() && 0 == info.height()) {
-        return SkImage_Raster::NewEmpty();
-    }
-    // check this after empty-check
-    if (NULL == pixels) {
+    if (!SkImage_Raster::ValidArgs(info, rowBytes) || !pixels) {
         return NULL;
     }
 
@@ -187,14 +168,7 @@ SkImage* SkImage::NewRasterCopy(const SkImageInfo& info, const void* pixels, siz
 
 
 SkImage* SkImage::NewRasterData(const SkImageInfo& info, SkData* data, size_t rowBytes) {
-    if (!SkImage_Raster::ValidArgs(info, rowBytes)) {
-        return NULL;
-    }
-    if (0 == info.width() && 0 == info.height()) {
-        return SkImage_Raster::NewEmpty();
-    }
-    // check this after empty-check
-    if (NULL == data) {
+    if (!SkImage_Raster::ValidArgs(info, rowBytes) || !data) {
         return NULL;
     }
 
diff --git a/src/image/SkSurface.cpp b/src/image/SkSurface.cpp
index dca4ce771c..6fd40c10af 100644
--- a/src/image/SkSurface.cpp
+++ b/src/image/SkSurface.cpp
@@ -123,16 +123,16 @@ static SkSurface_Base* asSB(SkSurface* surface) {
 SkSurface::SkSurface(int width, int height, const SkSurfaceProps* props)
     : fProps(SkSurfacePropsCopyOrDefault(props)), fWidth(width), fHeight(height)
 {
-    SkASSERT(fWidth >= 0);
-    SkASSERT(fHeight >= 0);
+    SkASSERT(fWidth > 0);
+    SkASSERT(fHeight > 0);
     fGenerationID = 0;
 }
 
 SkSurface::SkSurface(const SkImageInfo& info, const SkSurfaceProps* props)
     : fProps(SkSurfacePropsCopyOrDefault(props)), fWidth(info.width()), fHeight(info.height())
 {
-    SkASSERT(fWidth >= 0);
-    SkASSERT(fHeight >= 0);
+    SkASSERT(fWidth > 0);
+    SkASSERT(fHeight > 0);
     fGenerationID = 0;
 }
 
diff --git a/src/image/SkSurface_Raster.cpp b/src/image/SkSurface_Raster.cpp
index b221c130e5..2bac3f3156 100644
--- a/src/image/SkSurface_Raster.cpp
+++ b/src/image/SkSurface_Raster.cpp
@@ -39,6 +39,10 @@ private:
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkSurface_Raster::Valid(const SkImageInfo& info, size_t rowBytes) {
+    if (info.isEmpty()) {
+        return false;
+    }
+
     static const size_t kMaxTotalSize = SK_MaxS32;
 
     int shift = 0;
diff --git a/src/lazy/SkDiscardablePixelRef.cpp b/src/lazy/SkDiscardablePixelRef.cpp
index c4e3654d1a..84152ed188 100644
--- a/src/lazy/SkDiscardablePixelRef.cpp
+++ b/src/lazy/SkDiscardablePixelRef.cpp
@@ -98,6 +98,7 @@ bool SkInstallDiscardablePixelRef(SkImageGenerator* generator, SkBitmap* dst,
     SkAutoTDelete<SkImageGenerator> autoGenerator(generator);
     if ((NULL == autoGenerator.get())
         || (!autoGenerator->getInfo(&info))
+        || info.isEmpty()
         || (!dst->setInfo(info))) {
         return false;
     }